The present invention relates to a shackle, preferably for securing a wing to the fuselage of an aircraft or a spacecraft. Many different constructions of shackle devices are known in the art and such devices are used for many different purposes. Thus, shackles are used, for example, to interconnect chains. However, in certain countries, for example, in Germany, the industrial standards require that shackles for interconnecting chains are used only as a temporary, makeshift connecting element. Such a requirement is understandable if one takes into account that due to the use of high strength chain materials the dimensions of the individuell chain links have been reduced substantially, whereas the dimensions of prior art shackles cannot be reduced without special precautions, because otherwise the respective strength values of the shackle would be heavily influenced by such reduced shackle dimensions. In order to overcome this limitation of prior art shackles, special shackle constructions have been developed heretofore which are compact and which also have the necessary structural strength.
Thus, German Patent Publication (DAS No. 11 40 411) discloses a chain lock comprising an intermediate element constructed as a ring bandage. The ring bandage is latched to the leg ends extending into the bandage, by means of cross pins. Such cross pins are intended to securely take up any occurring bending forces and to provide a substantial variability in the size or dimensions of the chain lock. However, this type of prior art structure is not designed to substantially reduce the weight of the shackle structure because the forces to be taken up by the shackle determine the dimension of the force transmitting elements of the shackle as well as the selection of material of which the shackle is made. Thus, where the forces to be taken up are rather large as is the case in aircraft and spacecraft manufacture, it is necessary to make the just described type of chain lock with rather large dimensions which necessarily result in a heavy weight of the structure.
German Pat. No. 292 705 discloses a spring elastic shackle having a bail for taking up the tensile forces, for example, when pulling railroad cars or mine trollies. The bail is constructed as a screw spring, the spring excursion of which is limited by a rigid insert. However, these features also do not provide an improvement of the weight ratios and the dimension ratios, because the bending forces to be taken up by the holding eyelets and by the cross axle require a very certain dimensioning which cannot be reduced. The only purpose of using a screw spring as a tension bail in the prior art shackle is to make the shackle adaptable for different types of transportation vehicles.